Microtoner formulations having blended copolymers of a first and second resin and method of producing same

ABSTRACT

A microtoner (C) and method for producing same ( 10 ) is presented. The microtoner (C) includes a blend of at least one polymer (P 1 , P 2 , . . . and P N ) and at least one thermoplastic polymer (P 1 , P 2 , . . . and P N ). The method ( 10 ) of producing microtoner (C) includes blending ( 12 ) the at least one polymer with the at least one thermoplastic polymer and with one or more pigments to thereby form a dry mix toner formulation (T). The toner formulation (T) is pulverized ( 18 ) by mechanical means into an unclassified particulate microtoner (U). The unclassified particulate microtoner is then classified to produce the microtoner (C).

FIELD OF THE INVENTION

The present invention relates to toner for use in electrophotographic processes and/or printing machines, and a method for producing such toner particles.

BACKGROUND OF THE INVENTION

The toner used in electrophotographic printing machines is a blend of materials, including plastic binder resins, coloring pigments, such as, for example, carbon black, magnetic iron oxides, waxes, and charge control agents and other ingredients. Most toners are produced in bulk using a melt mixing or hot compounding process. The plastic binder resins, coloring pigments and other ingredients are blended together while in a molten state to thereby form a hot paste having a consistency similar to cake mix. This mixture is then cooled, typically, by forming it into slabs on a cooling belt or by pelletizing the mixture and cooling the pellets. The raw toner is then ground or pulverized into a toner powder by, for example, jet mills or air-swept hammer mills.

This process produces a toner powder having a wide range or distribution of particle sizes. Generally, toner having a narrow distribution of relatively small or fine particle sizes is preferable in that such toner produces higher-quality images. Therefore, the toner powder is sifted or classified to remove over-size and under-size toner particles. A toner powder having a relatively narrow distribution around a desired particle size is thus produced. The toner powder is then blended with additives to adjust various properties, such as, for example, flow, and electrostatic properties, and packaged for use.

Since the binder resin is the dominant component of toner formulations, typically constituting greater than eighty percent and often greater than ninety percent by weight of the toner formulation, the fracture mechanics of the binder resin is the limiting factor in reducing toner particle size. The fracture mechanics of the binder resin also limits the rate at which a given particle size is obtained. Further, as the particle size of the binder resin decreases the rate at which particle size reduction occurs also decreases.

Toner binders are typically mechanically reduced (i.e., by non-chemical methods, such as, for example, by grinding, milling, or pulverizing) to a volume median particle size of from approximately 6 to approximately 12 microns (μ), and the particles are then classified to produce a toner having a desired particle-size distribution. Mechanically reducing toner binder resin particles to a size of less than approximately 5μ is relatively inefficient due to the reduced rate at which particle-size-reduction occurs in such small-size particles. Thus, in general, it is not economically feasible to produce a toner powder with toner binder resin particles that have been mechanically reduced to particle sizes of approximately 5μ or less. Further, the relatively wide particle-size distribution that results from mechanically reducing toner binder resin particles to particle sizes of approximately 5μ or less makes classification of the particles into a narrow distribution of particle sizes difficult. Certain chemical processing methods are capable of producing such small binder resin particle sizes and narrow particle size distributions. However, the chemical methods require the purchase, storage, handling, and disposal of chemicals that may be hazardous or toxic. Further, the chemical methods must be closely controlled and monitored, and are not as environmentally friendly as the mechanical methods.

Therefore, what is needed in the art is a toner formulation that enables the production by mechanical particle size reduction methods of a toner having a volume-average particle size of the same order of magnitude as the volume-average particle size produced by chemical particle size reduction processes.

Furthermore, what is needed in the art is a method of producing a toner using mechanical particle size reduction processes and achieving a volume-average particle size of the same order of magnitude as the volume-average particle size produced by chemical particle size reduction processes.

SUMMARY OF THE INVENTION

The present invention provides a particulate microtoner and method for producing same.

The invention comprises, in one form thereof, a microtoner including a blend of at least one polymer and at least one thermoplastic polymer. The method of producing the microtoner includes blending the at least one polymer with the at least one thermoplastic polymer and with one or more pigments to thereby form a toner formulation. The toner formulation is pulverized by mechanical means into an unclassified particulate microtoner. The unclassified particulate microtoner is then classified.

An advantage of the present invention is that a microtoner having a volume-median particle size approximately equal to the particle sizes achieved by chemical particle size reduction methods is produced using conventional mechanical non-chemical particle size reduction means and/or methods.

A further advantage of the present invention is that the microtoner has a particle size distribution that is desirably smaller or tighter than the particle size distribution of conventional microtoner produced by conventional means.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become apparent and be better understood by reference to the following description of one embodiment of the invention in conjunction with the accompanying drawings, wherein:

FIG. 1 shows one embodiment of a method for producing toner of the present invention;

FIG. 2 shows one embodiment of an apparatus for producing toner of the present invention;

FIG. 3 is a plot of the volume median particle size distribution of the two blended-polymer binders;

FIG. 4 is a plot of the particle size dispersity index of the blended-polymer binders of FIG. 3; and

FIG. 5 is a plot of the particle size distribution for a conventional toner and for one embodiment of a toner of the present invention.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to FIGS. 1 and 2, there is respectively shown one embodiment of a method and one embodiment of an apparatus for producing toner of the present invention. Method 10 includes the processes of dry blending 12, melt mixing 14, extruding 16, particle size reduction 18 and classifying 20.

Dry blending process 12 includes the blending together of more than one polymer binder resin P₁, P₂, . . . and P_(N), at least one of which is a thermoplastic binder resin, with other ingredients generally designated A that are conventionally used in toner, such as, for example, colorants, charge control agents, waxes, and other additives to produce a dry blend toner formulation or dry mix T. The polymer binders P₁, P₂, . . . and P_(N) and the other ingredients/additives A are mixed or blended together using a blender 22 (FIG. 2), such as, for example, a high-speed blender manufactured by Henschel Industrietechnik GmbH.

Polymer binder resins P₁, P₂, . . . and P_(N) include polyesters, polyamides, polyolefins, acrylic polymers and copolymers, methacrylic polymers and copolymers, styrenic polymers and copolymers, vinyl polymers and copolymers, and polyurethanes. If two polymer binder resins P₁ and P₂ of the same chemical composition are blended together to form blended-polymer dry mix T, it is not necessary to have a difference in the physical composition of the polymer resin binders. However, it is preferable that the polymer binder resins P₁ and P₂ have different physico-chemical compositions. The blend of polymer binder resins suitable for use in blended-polymer dry mix T may also be achieved by multi-block copolymer polymerization.

Dry mix toner formulation T is approximately 1 to approximately 30 percent by weight of one or more colorants, and approximately 70 to approximately 99 percent by weight of the combined polymer binder resins P₁, P₂, . . . and P_(N). Preferably, dry mix T is approximately 4 to approximately 20 percent by weight of one or more colorants, and approximately 80 to approximately 96 percent by weight of combined polymer binder resins P₁, P₂, . . . and P_(N). Most preferably, dry mix T is approximately 6 to approximately 10 percent by weight of one or more colorants, and approximately 90 to approximately 94 percent by weight of combined polymer binder resins P₁, P₂, . . . and P_(N). Dry mix T may also include ingredients, such as, for example, a charge agent, waxy-like release agent, or other additives.

Dry mix T, when made with two polymer binder resins, is approximately 5 to approximately 95 percent by weight of first thermoplastic polymer P₁ and approximately 95 to approximately 5 percent by weight of second thermoplastic polymer P₂. Preferably, dry mix T is approximately 20 to approximately 40 percent by weight of first thermoplastic polymer P₁ and approximately 80 to approximately 60 percent by weight of second thermoplastic polymer P₂.

Melt mixing process 14 is carried out by processing blended-polymer dry mix T through a conventional melt mixing apparatus 24, such as, for example, an extruder, roll mill or kneading mill, at conventional melt mixing temperatures of approximately 60° C. to approximately 160° C. and preferably approximately 120° C. Thereafter, extruding process 16 is similarly carried out by conventional methods/means thereby producing toner extrudate E.

Particle size reduction process 18 is then conducted upon extrudate E. Particle size reduction process 18 utilizes conventional particle size reduction apparatus 26, such as, for example, a jet mill, air mill, pulverizer, or grinder, and conventional particle size reduction process parameters to reduce the particle size of toner extrudate E. For example, particle size reduction apparatus 26 is accomplished by processing extrudate E with a jet mill pulverizer operating with a pressure of less than 200 pounds per square inch (psi.) and preferably below approximately 115 psi. Raw and unclassified toner U produced by particle size reduction process 18 is then provided to classifying process 20.

Classifying process 20 is also carried out using a conventional cyclone apparatus 28 and/or classifying apparatus 30 as required or preferred. The undesirably fine and/or dust particles, often referred to collectively as super-fine particles, contained within unclassified toner U are carried by a pressurized flow of air or gas from cyclone 28 into a dust collector 32. The classifier 30 receives the remainder of the unclassified toner U from cyclone 28, sorts or classifies the unclassified toner U based on particle size, and delivers classified toner powder C having a desired range of particle sizes (i.e., classified product) to other processing equipment, such as, for example, a bulk container or bulk container-filling apparatus (not shown).

As illustrated in the following Examples, by performing method 10 generally, and particle size reduction process 18 particularly, upon toner extrudate E formed from the blended-polymer dry mix toner formulation T of the present invention the volume median particle size achieved is significantly less than the volume median particle size that is achieved by a substantially-identical particle size reduction process performed on a conventional toner extrudate having a single polymer binder resin. Further, a tighter particle size distribution is obtained along with a desirable and significant reduction in fine and super fine particles.

General Blended Polymer Example

A first plurality of blended-polymer toner batches, collectively referred to hereinafter as B1, absent any pigment was prepared by melt blending two resins and a charge control agent at approximately 115-120° C. on a two roll mill. The first polyester being a Binder W-85 very similar to a propoxylated bisphenol A-terephthalic acid based polyester, and the second polyester being a Binder C very similar to a propoxylated bisphenol A, a fumaric/maleic acid based polyester, both marketed as toner binder resins and available from Kao Corporation of Tokyo, Japan. The charge control agent, Bontron E-84 available from Orient Chemical Corporation of Japan, was present at the same concentration, i.e., approximately 3 parts per hundred (pph).

A second plurality of blended-polymer toner batches, collectively referred to hereinafter as B2, of clear toner was similarly prepared by melt blending two resins and a charge control agent at approximately 115-120 ° C. on a two roll mill. The first polyester in this second batch of toner was also Binder W-85, as described above, and the second Binder TF-90, very similar to a terpolymer of propoxylated bisphenol A-terephthalic acid and fumaric acid based polyester, also available from Kao Corporation of Tokyo, Japan. The charge control agent, Bontron E-84 available from Orient Chemical Corporation of Japan, was present at a concentration of approximately 3 parts per hundred (pph).

The ratio of the first binder to the second binder in each batch of the plurality of blended-polymer toner batches B1 and B2 is varied from 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100.

Referring now to FIG. 3, the volume median particle sizes for the first and second blended-polymer toner batches B1 and B2 are plotted against the percentage of the second binder type present in each toner batch. As shown in FIG. 3, it is seen that when either toner batch contains none of the second binder type (i.e., containing zero percent of the second binder type which corresponds to the vertical axis of the FIG. 3 plot) that toner batch is ground to a substantially smaller particle size than a toner batch containing none of the first binder type (i.e., containing one-hundred percent of the second toner which corresponds to the extreme right-hand side of the FIG. 3 plot). Thus, FIG. 3 shows that the first binder type and/or a toner containing substantially only the first binder type is reduced or ground to a significantly smaller particle size than the second binder type and/or a toner containing only the second binder type. Further, adding relatively small amounts, such as, for example, less than approximately fifty percent, of the second binder type to a toner batch does not significantly adversely affect (i.e., does not significantly increase) the particle sizes to which the toner batches are reduced or ground.

Moreover, and as best shown in FIG. 4, toner batches that have a certain percentage or range of percentages of the second binder type exhibit a desirably reduced (i.e., narrower) particle size dispersity index (PSDI). PSDI is defined as the ratio of the volume median particle size of toner particles to the number median particle size thereof. As FIG. 4 shows, toner that includes a certain concentration, such as, for example, from approximately ten to approximately sixty percent, of a second binder type has a significantly and desirably reduced (i.e., narrowed) particle size distribution and a more desirably PSDI.

Thus, it is shown that a desirable reduction in volume median particle size and a desirable reduction in particle size distribution are achieved when mechanically reducing or grinding a toner formed from a blend of more than one polymer.

EXAMPLE 1

A conventional, single polymer toner extrudate was prepared by melt blending in a 30 millimeter (mm) twin-screw extruder Regal 330 carbon black pigment, obtained from by Cabot Corporation, Billerica, Mass., USA, with Binder C polyester, obtained from Kao Corporation of Tokyo, Japan, and with 2 parts per hundred (pph) Bontron E-84 charge agent such that the final pigment concentration was 4.5 parts of pigment per 100 parts resin by weight. The pigment concentration was chosen for specific calorimetric properties not pertinent to the invention. The toner extrudate was cooled out of the extruder using a chill-belt and granulated in a Wiley-type mill into granules of approximately 500 microns in size.

The above described granulated black toner extrudate was then pulverized using a Hosokawa-Alpine 200 AFG jet mill pulverizer at a nozzle pressure of approximately 80 pounds per square inch and an average rotor speed of approximately 11,500 revolutions per minute to produce an unclassified toner.

The unclassified toner had a volume-median particle size of approximately 5.26 microns and a number-median particle size of approximately 3.44 microns as measured on a Coulter Mutlisizer with a 70μ aperture. Thus, a particle size dispersity index (PSDI), which is the ratio of the volume-median particle size to the number-median particle size, of 1.53 was obtained.

It is to be understood that the model number of the mill is specific to the size of the mill, and is independent of the experimental data presented herein.

EXAMPLE 2

A second conventional single-polymer toner extrudate was prepared by melt blending in a 30 mm twin-screw extruder Regal 330 carbon black pigment, obtained from Cabot Corporation, Billerica, Mass. USA, with Binder W-85 polyester, obtained from Kao Corporation of Tokyo, Japan, and with 2 pph Bontron E-84 charge agent such that the final pigment concentration was 6.0 parts of pigment per 100 parts resin by weight. The pigment concentration was chosen for specific colorimetric properties not pertinent to the invention. The toner extrudate was cooled out of the extruder through a chill-belt and granulated in a Wiley-type mill into granules of approximately 500 microns in size.

The above-described granulated black toner extrudate was then pulverized using a Hosokawa-Alpine 200 AFG jet mill pulverizer at a nozzle pressure of approximately 80 psi with an average rotor speed of approximately 10,500 revolutions per minute. An unclassified toner was produced having a volume-median particle size of approximately 3.77 microns (μ) and a 2.46 number-median particle size as measured on a Coulter Multisizer with a 30μ aperture. Thus, a particle size dispersity index of 1.53 was also obtained.

ANALYSIS OF EXAMPLES 1 AND 2

Comparing the above examples shows that substantially identical pulverization processes were applied to the conventional single-polymer toner extrudates of Examples 1 and 2, and yet the unclassified toner produced in Example 2 had a smaller volume-median particle size (approximately 3.46μ) than the unclassified toner produced in Example 1. It should be particularly noted, however, that the unclassified toner produced in Example 2 had a significantly higher amount of super-fine particulates (i.e., particles of less than approximately 2 microns) than the unclassified toner produced in Example 1. The higher amount of super-fine particulates makes classification of the unclassified toner produced in Example 2 a more difficult, time consuming and costly process. Thus, although a desirably smaller volume-median particle size was achieved in Example 2, a less desirable particle size distribution resulted.

The pulverization rates of both batches of granulated black toner extrudate were approximately 3 kilograms per hour. The pulverization rate, in general, was limited by the practical limit of the rotor speed, which, in turn, limits the particle size. Thus, the pulverization rate is indicative of the lower limit of fracture size for the toner formulation/extrudate.

INVENTIVE EXAMPLE 1

In contrast to the above examples, the method of the present invention processes blended-polymer dry mix T through the same or substantially the same conventional non-chemical pulverizing methods and/or processes, and yet produces an unclassified toner U desirably having a smaller volume-median particle size, a tighter distribution of particle sizes, and a significantly smaller amount of super-fine particles.

More particularly, extrudate E was prepared by melt blending in a 30 mm twin-screw extruder Regal 330 carbon black pigment, obtained from Cabot Corporation of Billerica, Mass., U.S.A., with 2 pph Bontron E-84 charge agent, and with a blend of two polyesters. The polyesters in this exemplary embodiment were Binder C and binder W-85, both of which were obtained from Kao Corporation of Tokyo, Japan. The ratio of the two polyesters was 20 percent to 80 percent of the 100 parts total resin. The final pigment concentration was 6.0 parts of pigment per 100 parts resin by weight. The pigment concentration was chosen for specific colorimetric properties not pertinent to the invention. The toner extrudate E was cooled out of the extruder through a chill-belt, and granulated in a Wiley-type mill into granules of approximately 500 micron in size.

The above-described granulated black toner extrudate E was then pulverized on a Hosokawa-Alpine 200 AFG jet mill pulverizer, using a nozzle pressure of approximately 80 psi, an average rotor speed of approximately 11,500 revolutions per minute, and a bed level indicted by the rotor current of 2.6 amps. An unclassified toner powder U was thereby produced having a volume-median particle size of approximately 3.72 microns and a 2.61 number-median particle size as measured on a Coulter Multisizer using a 30 micron aperture. Thus, a particle size dispersity index of 1.42 was also obtained.

Discussion

Referring now to FIG. 5, the volume and number particle size distributions for the unclassified toner powder U of inventive example 1 are plotted. More particularly, the volume distribution for the unclassified blended-polymer toner powder U of inventive example 1 is shown by curve V₁ and the number particle size distribution for the unclassified blended-polymer toner powder U of inventive example 1 is shown by curve N₁. Similarly, FIG. 5 also plots as curves V₂ and N₂, respectively, the volume particle size distribution and the number particle size distribution for the conventional (unclassified) toner described above in Example 2. Comparing the plots, it is seen that the volume distribution curve V₁ for the unclassified blended-polymer toner powder U of inventive example 1 has a peak at a smaller volume average particle size than the peak of the volume distribution curve V₂ for the conventional (unclassified) toner described above in Example 2.

Further, as FIG. 5 shows, for particle size values of less than approximately two microns the number particle size distribution curve N₁ for the unclassified blended-polymer toner powder U of inventive example 1 lies above the number particle size distribution curve N₂ for the conventional toner of Example 2. Since the area under each of curves N₁ and N₂ indicates the number of particles of a given size, and since for particle sizes of less than approximately 2μ the area under curve N₁ is less than the area under curve N₂, it is shown that the toner of inventive Example 1 has a substantially reduced number of fine or super fine particles.

It should be particularly noted that the dashed-line extensions of curves N₁ and N₂ of FIG. 5 represent and generally correspond to extrapolations of a “best case” condition in terms of the quantity of particles having a particle size of less than approximately 1 micron for curve N₁. In practice, curve N₁ is likely to become more horizontal in nature, and may even reverse its slope to a positive value and at least temporarily trend upward. Thus, it is likely that the toner of Example 1 will undesirably contain a significantly greater number of fine and super fine particles than is shown by FIG. 5, and therefore inventive example 1 is likely to be significantly more advantageous than illustrated therein.

In summary, the unclassified blended-polymer toner powder U of inventive example 1 has a desirably smaller volume median particle size and desirably has significantly fewer fine and super fine particles than conventional single-polymer toners. The unclassified blended-polymer toner powder U of inventive example 1 is therefore more readily and less expensively classified than conventional single-polymer toners. Furthermore, it is seen that the lower limit of volume-median particle size that can be achieved from conventional pulverizing and microtoner processing equipment and methods is reduced by using a blended-polymer dry mix T that has a lower limit of fracture size.

Table 1 summarizes the above results: TABLE 1 Volume median Number Median Particle size Particle Size Toner (μ) (μ) PSDI Example 1 5.26 3.44 1.53 Example 2 3.77 2.46 1.53 Inventive 3.72 2.61 1.42 Example 1

In the embodiments shown and described, two polymer binder resins are combined to produce a dry mix T having a reduced particle size, tighter particle size distribution, and fewer fine and super fine particles relative to conventional single-polymer toners. The binders are generally described as being present from approximately 5 to approximately 95 percent by weight for the first thermoplastic polymer and approximately 95 to approximately 5 percent by weight of the second thermoplastic polymer. However, it is to be understood that similar benefits can be achieved by adding or mixing as little as one percent of a second polymer to a first polymer or by adding/synthesizing a multi-block copolymer for use in and/or addition to the mix. The particular proportions of the mix and the benefits obtained are dependent upon the specific polymers involved and their respective physical properties and fracture mechanics.

In the embodiments shown, the process of producing the toner of the present invention blends the polymers prior to the melt mixing operation/process. However, it is to be understood that the process can be alternately configured, such as, for example, blending the polymers before or during the melt mix and extruding processes, and/or before the pulverization process.

While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the present invention using the general principles disclosed herein. Further, this application is intended to cover such departures from the present disclosure as come within the known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Parts List

-   10. Process -   12. Dry Blend Process -   14. Melt mixing process -   16. Extruding process -   18. Pulverizing process -   20. Classifying -   22. Blender -   24. Melt Mixer -   26. Particle size reducing apparatus -   P₁, P₂, P₃ . . . P_(N)—Polymer Binder Resins -   B1 B2—Toner batches -   T—Dry Mix Toner Formulation -   A—Additives -   E—Extrudate -   U—Unclassified Toner -   C—Classified Toner 

1. A microtoner formulation, comprising: a polymer blend including at least one polymer and at least one thermoplastic polymer.
 2. The microtoner formulation of claim 1, wherein said polymer and said thermoplastic polymer are each individually selected from the group consisting essentially of polyesters, polyamides, polyolefins, acrylic polymers and copolymers, methacrylic polymers and copolymers, styrenic polymers and copolymers, vinyl polymers and copolymers, and polyurethanes.
 3. The microtoner formulation of claim 1, further comprising one or more pigments, said pigments comprising from approximately two to approximately thirty percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-eight to approximately seventy percent by weight of said microtoner formulation.
 4. The microtoner formulation of claim 3, wherein said one or more pigments comprise from approximately four to approximately twenty percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-six to approximately eighty percent by weight of said microtoner formulation.
 5. The microtoner formulation of claim 3, wherein said one or more pigments comprise from approximately six to approximately ten percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-four to approximately ninety percent by weight of said microtoner formulation.
 6. The microtoner formulation of claim 3, wherein said polymer blend comprises from approximately five to approximately ninety-five percent by weight of a first polymer, and from approximately ninety-five to approximately five percent by weight of a second polymer.
 7. The microtoner formulation of claim 3, wherein said polymer blend comprises from approximately twenty to approximately forty percent by weight of a first polymer, and from approximately eighty to approximately sixty percent by weight of a second polymer.
 8. The microtoner formulation of claim 3, wherein each of said at least one polymer and said at least one thermoplastic polymer comprise thermoplastic polymers.
 9. The microtoner formulation of claim 8, wherein said polymers are the same thermoplastic polymer but with different fracture properties.
 10. The microtoner formulation of claim 8, wherein said polymers are different thermoplastic polymers.
 11. A method of forming a particulate microtoner for use in the development of electrophotographic images, comprising: blending at least one polymer with at least one thermoplastic polymer and with one or more pigments to thereby form a toner formulation; pulverizing by mechanical means the toner formulation into an unclassified microtoner powder; and classifying the unclassified microtoner formulation.
 12. The method of forming a particulate microtoner of claim 11, wherein said blending step comprises: dry blending said at least one polymer with said at least one thermoplastic polymer and said one or more pigments to thereby form a dry mix; melt mixing the dry mix; and extruding the melt mix.
 13. The method of forming a particulate microtoner of claim 11, wherein said blending step comprises: melt mixing one of said at least one polymer and said at least one thermoplastic polymer with said one or more pigments; adding the other of said at least one polymer and said at least one thermoplastic polymer to said melt mix and further melt mixing; and extruding the melt mix.
 14. The method of forming a particulate microtoner of claim 11, wherein said at least one polymer and said at least one thermoplastic polymer are each individually selected from the group consisting essentially of polyesters, polyamides, polyolefins, acrylic polymers and copolymers, methacrylic polymers and copolymers, styrenic polymers and copolymers, vinyl polymers and copolymers, and polyurethanes.
 15. The method of forming a particulate microtoner of claim 11, wherein said one or more pigments comprise from approximately two to approximately thirty percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-eight to approximately seventy percent by weight of said microtoner formulation.
 16. The method of forming a particulate microtoner of claim 11, wherein said one or more pigments comprise from approximately four to approximately twenty percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-six to approximately eighty percent by weight of said microtoner formulation.
 17. The method of forming a particulate microtoner of claim 11, wherein said one or more pigments comprise from approximately six to approximately ten percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-four to approximately ninety percent by weight of said microtoner formulation.
 18. The method of forming a particulate microtoner of claim 11, wherein said polymer blend comprises from approximately five to approximately ninety-five percent by weight of a first polymer, and from approximately ninety-five to approximately five percent by weight of a second polymer.
 19. The method of forming a particulate microtoner of claim 11, wherein said polymer blend comprises from approximately twenty to approximately forty percent by weight of a first polymer, and from approximately eighty to approximately sixty percent by weight of a second polymer.
 20. The method of forming a particulate microtoner of claim 11, wherein each of said at least one polymer and said at least one thermoplastic polymer comprise thermoplastic polymers.
 21. The method of forming a particulate microtoner of claim 20, wherein said polymers are the same thermoplastic polymer.
 22. The method of forming a particulate microtoner of claim 20, wherein said polymers are different thermoplastic polymers.
 23. The method of forming a particulate microtoner of claim 11, wherein said pulverizing process is carried out by a conventional method using conventional process parameters, and produces a particulate microtoner having a volume-median particle size of less than approximately 12 microns.
 24. The method of forming a particulate microtoner of claim 23, wherein said pulverizing process is carried out by a conventional method using conventional process parameters, and produces a particulate microtoner having a volume-median particle size of less than approximately 6 microns.
 25. The method of forming a particulate microtoner of claim 24, wherein said pulverizing process is carried out by a conventional method using conventional process parameters, and produces a particulate microtoner having a volume-median particle size of less than approximately 5 microns.
 26. The method of forming a particulate microtoner of claim 25, wherein said pulverizing process is carried out by a conventional method using conventional process parameters, and produces a particulate microtoner having a volume-median particle size of less than approximately 4 microns.
 27. The method of forming a particulate microtoner of claim 23, wherein said mechanical means of pulverizing comprises a jet mill pulverizer.
 28. A method for producing particulate microtoner having an improved unclassified particle size distribution relative to the unclassified particle size distribution of a particulate microtoner produced by conventional methods, comprising: blending at least one polymer with at least one thermoplastic polymer and with one or more pigments to thereby form a toner formulation; and pulverizing by mechanical means the toner formulation into an unclassified microtoner powder.
 29. The method of claim 28, wherein said blending step comprises: dry blending said at least one polymer with said at least one thermoplastic polymer and said one or more pigments to thereby form a dry mix; melt mixing the dry mix; and extruding the melt mix.
 30. The method of claim 28, wherein said blending step comprises: melt mixing one of said at least one polymer and said at least one thermoplastic polymer with said one or more pigments; adding the other of said at least one polymer and said at least one thermoplastic polymer to said melt mix and further melt mixing; and extruding the melt mix.
 31. The method of claim 28, wherein said at least one polymer and said at least one thermoplastic polymer are each individually selected from the group consisting essentially of polyesters, polyamides, polyolefins, acrylic polymers and copolymers, methacrylic polymers and copolymers, styrenic polymers and copolymers, vinyl polymers and copolymers, and polyurethanes.
 32. The method of claim 28, wherein said one or more pigments comprise from approximately two to approximately thirty percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-eight to approximately seventy percent by weight of said microtoner formulation.
 33. The method of claim 28, wherein said one or more pigments comprise from approximately four to approximately twenty percent by weight of said microtoner formulation, and said polymer blend comprises from approximately ninety-six to approximately eighty percent by weight of said microtoner formulation.
 34. The method of claim 28, wherein said mechanical means comprises a jet mill pulverizer. 